High-pressure air and steam are used in various industrial applications. For example, extremely high-pressure air may be used on submarines for clearing main ballast tanks. High-pressure water vapor (commonly referring to water molecules with or without air or other gas molecules present) can also be used to create a very effective high-pressure chemical reaction with a purpose of reducing various components of the reaction down to their fundamental constituents of water and carbon dioxide. For example, this technique is used in the process of supercritical water oxidation (SCWO), wherein diverse waste streams, including sewage, commercial waste, old munitions, and the like, are converted to basic oxidized constituents with minimal harmful waste effluent from the process.
Conventional forms of compression for such high-pressure applications have been accomplished with positive displacement compressors originally designed for submarines and that provide pressures in the order of 5,000 psi. Such conventional compressors limit the possibilities of efficient recapture of waste energy and reinsertion of the energy back into the cycle.
Various processes for treating a feedstock require process materials to be maintained at elevated pressures. Additionally, conventional processes may require the feedstock to be at an elevated temperature. In such treatment processes, obtaining a high-pressure rise with minimum energy consumption presents a continuing problem. One of the efforts to recover waste energy in current systems involves the use of conventional turbines to expand the high-pressure gas effluent stream once the reaction is complete. The energy recaptured is then delivered to an electric generator. The electric power created in the generator is either used to drive the high-pressure positive displacement compressors or is returned to the grid.
Inefficient use of waste energy has been particularly acute in the hydrothermal treatment of organic waste products using SCWO techniques. In a typical SCWO process, the materials in a reaction chamber are preferably maintained at a pressure of over 200 bar and a temperature of over 700° Celsius. Processes may have a preferred reaction pressure of 1000 bar. Conventional positive displacement compressors, as described above, are used to help achieve such high-pressures in the reaction chamber.
In SCWO processes, oxidation of waste organics can be achieved by pumping an oxidizer, such as air, into the reaction chamber for mixing with other constituents of the reaction, such as supercritical water, raw wastes, and additives such as a fuel to assist in maintaining suitable temperatures. Such processes are described in U.S. Pat. No. 4,338,199 issued to Model on Jul. 6, 1982, U.S. Pat. No. 5,106,513 issued to Hong on Apr. 21, 1992, and U.S. Pat. No. 6,519,926 issued to Hazlebeck on Feb. 18, 2003, which are all hereby incorporated by reference in their entirety.
Multiple stage turboccharging of internal combustion engines is a technique well known in the art. For examples, such multiple stage turbocharging of internal combustion engines may be found in U.S. Pat. No. 7,000,393 issued to Wood et al. Additionally, multiple stage turbocharging of internal combustion engines is also provided in Turbocharging the Internal Combustion Engine, by N. Watson and M. S. Janota, at sections 11.5 and 11.6, published by Wiley-Interscience Division, John Wiley & Sons, Inc., New York (1982). However, the recovery of energy in such conventional systems has generally been inefficient.